<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <div v-if="age>=18">成年</div>
        <div v-else>未成年</div>
    </div>
    <script src="./vue.js"></script>
    <script>
        new Vue({
            el: "#app",
            data() {
                return {
                    age: 20
                }
            },
            methods: {

            }
        })
    </script>
</body>

</html>